This application claims priority to co-pending patent application Ser. No. 11/430,347, filed May 9, 2006, the entire disclosure of which is incorporated herein by reference. This application is owned by the owner of application Ser. No. 10/750,391, filed Dec. 31, 2003, now issued as U.S. Pat. No. 7,070,303, the entireties of which are also incorporated herein by reference.
1. Field of the Invention
The present invention relates to electrically powered lighting fixtures including fluorescent lighting fixtures adapted for use indoors or beneath a ceiling.
2. Discussion of the Prior Art
In order to make a large area visually comfortable, downlight fixtures often include some uplight capabilities, to reduce the “cave” effect caused by ceiling fixtures being too intense for the viewer to see the ceiling beyond the fixtures. The cave effect causes a glare-filled, enclosed effect, which increases eyestrain.
However, too much uplighting is inefficient and wasteful, not reflecting a large portion of emitted light back to the space below the fixture.
To provide uplight, it is known to have an open top, which wastes light usage, as much of the light is not reflected back to the space below the fixture. In addition, in general, however, lamp fixtures with open tops have a susceptibility to dirt accumulation.
Among related patents include U.S. Pat. No. 2,281,377 of Ohm, which has a slanted transparent/translucent wall but no reflector, which does not control uplight to a preferable maximum of 5-19% (by bent and concave angles of the reflector). Ohm's wall 13 is convex, so most light is not controlled. If a fixture were made similar to that of Ohm '377, wherein it would be fabricated without the lens, the fluorescent lamps would extend beyond the plane of the side of the fixture, allowing for excessive dirt accumulation thereon. Furthermore, if one would make a fixture similar to that of Ohm '377 with a non-translucent wall, the fixture efficiency would be greatly diminished. In addition, the lack of a photometrically designed reflector would diminish the obtainable efficiency of the fixture.
U.S. Pat. No. 2,534,182 of Schwartz has different angles for reflectors 31, 32, 33 that don't control uplighting. Their rounded lenses are not as efficient as using a flat lens.
In U.S. Pat. No. 2,548,500 of Sachs, the position of the reflector 15 beneath the fluorescent lamp tubes causes 50% of light up and 50% down, not a preferable controlled 5 19% as uptight. Also, if one removes the item 15 of Sachs, one accumulates dirt within the fixture.
U.S. Pat. No. 6,428,183B1 of McAlpin gets 100 percent of light up with visual waste and needs extra upper lamps 32,33 with separate mounts. These upper lamps are exposed and subject to dirt accumulation.
U.S. Pat. No. 5,806,967 of Soorus is mainly a V-shaped uptight fixture open at top, so dirt will invariably accumulate therein.
U.S. Pat. No. 2,545,058 of Walsh has an open top with susceptibility to dirt accumulation. Walsh is mainly uptight only as in FIG. 10 therein.
U.S. Pat. No. 2,474,341 of Wince doesn't have a reflector.
U.S. Pat. No. 2,348,930 of Shepmoes has a V-shape end view configuration of lamp fixtures. Downward light is less than 70%.
U.S. Pat. No. 2,327,230 of Weber is only concerned with access removal of the lens portion 27. Lighting inefficiency is similar to Shepnoes.
U.S. Pat. No. 2,320,829 of Naysmith and U.S. Pat. No. 2,323,002 of Baker both describe V-shaped arrangement of lamps, which does not control uplight.
Therefore, there is a need to provide a fluorescent lamp fixture which controls uplight to a desirable level, without wasting excess light, while significantly reducing an undesirable cave effect and without the tendency to accumulate dirt within the fixture.